<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>28伪元素选择器-使用场景</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        div {
            position: relative;
            width: 200px;
            height: 30px;
            border: 1px solid red;
        }
        
        div::after {
            position: absolute;
            top: 50%;
            right: 10px;
            margin-top: -3px;
            /* 注意conten不能忘记写 */
            content: "";
            width: 6px;
            height: 6px;
            border: solid black;
            border-width: 0 2px 2px 0;
            transform: rotate(-45deg);
            /* 向右的箭头 */
            -webkit-transform: rotate(-45deg);
            /* 向下的箭头 */
            /* -webkit-transform: rotate(45deg); */
        }
    </style>
</head>

<body>
    <div>伪元素选择器</div>
</body>

</html>